Introduction to Cloud Computing
Cloud computing is the delivery of computing services — including servers, storage, databases, networking, software, analytics, and intelligence — over the Internet (“the cloud”) to offer faster innovation, flexible resources, and economies of scale. Organizations pay only for the cloud services they use, helping lower operating costs, run infrastructure more efficiently, and scale as business needs change.
Key Characteristics (NIST-aligned)
Cloud computing typically provides:
- On-demand self-service — provision resources as needed without human interaction.
- Broad network access — services available over the network from various client platforms.
- Resource pooling — provider resources shared across multiple customers.
- Rapid elasticity — scale resources up or down quickly.
- Measured service — resource usage is monitored, controlled, and reported.
Service Models
There are three primary service models you should know for interviews:
IaaS (Infrastructure as a Service)
IaaS offers fundamental compute, storage, and networking resources on demand, e.g., AWS EC2, Azure Virtual Machines, Google Compute Engine. It gives maximum flexibility and control over the infrastructure.
PaaS (Platform as a Service)
PaaS provides managed platforms to develop, run, and manage applications without dealing with underlying infrastructure, e.g., Heroku, Google App Engine, AWS Elastic Beanstalk.
SaaS (Software as a Service)
SaaS delivers fully functional applications over the web, managed by the provider. Examples include Salesforce, Office 365, and Google Workspace. Users access software via browsers or APIs.
Deployment Models
Common deployment models:
- Public cloud — services offered over the public internet by third-party providers.
- Private cloud — cloud infrastructure operated solely for a single organization.
- Hybrid cloud — combination of public and private clouds, allowing data and application portability.
- Multi-cloud — use of multiple cloud providers to avoid lock-in or optimize cost/performance.
Security & Compliance Considerations
Security is a shared responsibility. Cloud providers secure the infrastructure, while customers are responsible for securing data, access controls, and applications. Important topics to be ready to discuss in interviews:
- Identity and Access Management (IAM)
- Encryption at rest and in transit
- Network segmentation and VPCs
- Compliance certifications (e.g., SOC 2, ISO 27001, GDPR)
- Monitoring, logging, and incident response
Simple Example (CLI)
Example: launching a compute instance with AWS CLI (simplified):
aws ec2 run-instances --image-id ami-0123456789abcdef0 --count 1 --instance-type t3.micro --key-name MyKeyPair --security-group-ids sg-01234567 --subnet-id subnet-89ab-cdef
When to Use Cloud
Choose cloud when you need rapid provisioning, variable workloads, global reach, or managed services (databases, analytics, AI/ML). For very sensitive data or strict latency/sovereignty requirements, consider private or hybrid approaches.
How to Answer This In an Interview
Keep your answer structured: define cloud computing, mention NIST characteristics, describe service and deployment models with examples, and highlight security and cost considerations. If possible, share a brief real-world example where cloud solved a business problem.
Prepared with these core points, you can confidently explain what cloud computing is and why organizations adopt it.